This invention relates to valve inserts and valves used to control intravenous flow of liquid to or from a patient.
It is common medical practice to insert an indwelling catheter into the vein of a patient, and tape the inserted catheter to the patient. The end of the catheter projecting from the patient carries a fitting which prevents the loss of blood, and permits medication to be administered to the patient, or blood samples to be taken from the patient, without requiring repeated puncturing of the patient. Such fittings are referred to as "intermittent caps" because they close the outer end of the indwelling catheter to prevent loss of blood from the patient, and yet permit intermittent intravenous access to the patient, as required.
The disadvantage of prior art intermittent caps, such as that shown in U.S. Pat. No. 4,083,916 to Raines (1987), is that they have relatively large flow paths open to contaminants when the caps are not in use. Such prior art caps are difficult, if not impossible, to sterilize immediately prior to each time medication is to be administered through them.
U.S. Pat. No. 3,500,821 to Ogle (1970) discloses blood sampling apparatus with aspiration means in which one end of a sharp-pointed cannula is covered by a rubber tube which permits blood to flow between the cannula exterior and tube interior when the device is in a patient and no blood sample is being taken.